operating instructions eex p control unit - Electromach BV

The purging time and switching values of the pressure switches are pre-set at the factory. This alsoapplies for relays K4/5.4.2 FUNCTION FOR UTILISATION AS A PRESSURISED ENCLOSURE WITHCONTINUOUS RINSINGAfter the safety mechanism is switched on, a pressure builds up in the housing.The pressure sensors in the display/measurement module monitor the internal pressure of the housingand the differential pressure on the measuring aperture. If the pre-set measurement values Min A + B andDiff A + B are exceeded, then the pre-set purging time starts. The relevant LED in the control unit lights upand the residual purging time in the display/measurement module tends towards zero.If too high a housing internal pressure is reached during the purging phase due to an impermissibly highflow resistance on the protective-gas output, the purging operation is terminated. It is only possible "afterelimination of the possible cause" to switch on again by pressing the switch S5 of the control module (turnto pos. 0, turn back to pos. 1).If a too low protective-gas flow is measured on Diff A or Diff B during the purging phase, then the residualpurging time is reset to the maximum purging time value.Please check the input pressure on the reducing valve, housing seal and doorlocks.After the purging time has elapsed, the voltage supply of the control unit is enabled via the contacts K2/K3on terminals 34 and 35. Contacts K4 and K5 switch in accordance with the configuration. The OperationLED in the control module lights up. The residual-purging-time display goes out and the existing housinginternal pressure is indicated on the sensor module.If the housing pressure falls below the switching value Min A or Min B during the operating phase, K2/3and the configured K4/5 are released. This switches off the power of any connected non-Ex devices.Simultaneously, a new pre-purging phase commences. The voltage is enabled after a time delay(approximately 5 seconds) in order to compensate any possible protective gas fluctuations in the mains.Please check the housing seal, the doorlocks and whether the input pressure is still adequate.PAGE 7/ 21